Developing device and image forming apparatus having the same

An image forming apparatus comprising:

• a photosensitive drum on which a toner image is formed;
• a developing device forming the toner image on the photosensitive drum;
• and
• a fixing unit fixing the toner image to a paper on which the toner image is transferred from the photosensitive drum;
• the developing device including:
• a developer storing section storing a developer;
• a stirring member disposed in the developer storing section and transporting the developer while stirring the developer;
• a developer carrier receiving the developer from the developer storing section and carrying the developer;
• a developer regulating member regulating the amount of the developer received by the developer carrier from the developer storing section;
• and
• a heat-dissipating member disposed at a position in contact with the developer and capable of dissipating heat of the developer;
• wherein the heat-dissipating member has a surface in contact with the developer, the contact surface having an arithmetic surface roughness Ra1 that is set to be equal to or less than ⅓ of the volume average particle size of toner particles contained in the developer.